Pollutant emission control sorbents and methods of manufacture and use

Abstract

Sorbents for removal of mercury and other pollutants from gas streams, such as a flue gas stream from coal-fired utility plants, and methods for their manufacture and use are disclosed. Embodiments include brominated sorbent substrate particles having a carbon content of less than about 10%. Other embodiments include one or more oxidatively active halides of a nonoxidative metal dispersed on sorbent substrate particles mixed with activated carbon in an amount up to 30% by weight.

What is claimed is: 
     
       1. A method of making brominated mineral sorbent powder for injection into a combustion gas in an exhaust gas system for removal of mercury from the combustion gas, the method comprising dispersing a bromide salt selected from sodium bromide, calcium bromide, potassium bromide, magnesium bromide, and combinations thereof onto mineral sorbent substrate particles by spray-drying a mixture of a slurry of the bromide salt and the mineral sorbent substrate particles to provide the powder for subsequent injection into the exhaust gas system containing mercury, the mineral sorbent substrate particles containing less than about 10 weight percent carbon. 
     
     
       2. The method of  claim 1 , wherein the substrate particle is selected from the group consisting of kaolin, metakaolin, fully calcined kaolin, and combinations thereof. 
     
     
       3. The method of  claim 2 , further comprising drying the particles having the bromide salt dispersed thereon at a temperature in the range of about 25° C. and about 200° C. 
     
     
       4. The method of  claim 1 , wherein the bromide salt has a loading level in the range of about 0.1 to about 20 weight percent. 
     
     
       5. The method of  claim 1 , wherein the bromide salt has a loading level in the range of about of about 3 to about 15 weight percent. 
     
     
       6. The method of  claim 4 , further comprising reducing the sorbent particle size to an average particle size of less than about 20 μm. 
     
     
       7. The method of  claim 1 , wherein the mineral sorbent substrate particles are selected from the group consisting of alumina, silica, titania, zirconia, iron oxides, zinc oxide, rare earth oxides, metal carbonate, metal sulfate, aluminosilicates, zeolites, kaolin, metakaolin, fully calcined kaolin, bentonite, attapulgite, talc, fly ash, dirt, and combinations thereof, the particles having a total carbon content less than about 10 weight percent. 
     
     
       8. The method of  claim 6 , wherein the mineral sorbent substrate particles are selected from the group consisting of kaolin, metakaolin, fully calcined kaolin, and combinations thereof.